diff --git a/libraries/base/GHC/Base.hs b/libraries/base/GHC/Base.hs
--- a/libraries/base/GHC/Base.hs
+++ b/libraries/base/GHC/Base.hs
@@ -413,12 +413,13 @@
-- | Lift a semigroup into 'Maybe' forming a 'Monoid' according to
-- : \"Any semigroup @S@ may be
-- turned into a monoid simply by adjoining an element @e@ not in @S@
--- and defining @e*e = e@ and @e*s = s = s*e@ for all @s ∈ S@.\" Since
--- there used to be no \"Semigroup\" typeclass providing just 'mappend',
--- we use 'Monoid' instead.
+-- and defining @e*e = e@ and @e*s = s = s*e@ for all @s ∈ S@.\"
+--
+-- /Since 4.11.0/: constraint on inner @a@ value generalised from
+-- 'Monoid' to 'Semigroup'.
--
-- @since 2.01
-instance Monoid a => Monoid (Maybe a) where
+instance Semigroup a => Monoid (Maybe a) where
mempty = Nothing
-- | For tuples, the 'Monoid' constraint on @a@ determines
diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md
--- a/libraries/base/changelog.md
+++ b/libraries/base/changelog.md
@@ -14,6 +14,9 @@
export `Semigroup` from `Prelude`; remove `Monoid` reexport
from `Data.Semigroup` (#14191).
+ * Generalise `instance Monoid a => Monoid (Maybe a)` to
+ `instance Semigroup a => Monoid (Maybe a)`.
+
* Add `infixl 9 !!` declaration for `Data.List.NonEmpty.!!`
* Add `<&>` operator to `Data.Functor` (#14029)
diff --git a/testsuite/tests/ghci/scripts/T4175.stdout b/testsuite/tests/ghci/scripts/T4175.stdout
--- a/testsuite/tests/ghci/scripts/T4175.stdout
+++ b/testsuite/tests/ghci/scripts/T4175.stdout
@@ -34,7 +34,7 @@
instance Eq a => Eq (Maybe a) -- Defined in ‘GHC.Base’
instance Functor Maybe -- Defined in ‘GHC.Base’
instance Monad Maybe -- Defined in ‘GHC.Base’
-instance Monoid a => Monoid (Maybe a) -- Defined in ‘GHC.Base’
+instance Semigroup a => Monoid (Maybe a) -- Defined in ‘GHC.Base’
instance Ord a => Ord (Maybe a) -- Defined in ‘GHC.Base’
instance Semigroup a => Semigroup (Maybe a)
-- Defined in ‘GHC.Base’